In a conventional machining system, a machining program creating device represented by a CAM creates a machining program based on a material shape, a product shape, a tool, or the like to perform desired machining and a numerical control device controls shafts of a machine tool and performs machining based on the machining program. In general, a relative moving route of a tool with respect to a material and command speed are commanded to the machining program. However, there are limits in speed and acceleration at which the machine tool can operate. For example, depending on feed driving systems and actuators of the shafts, there are limits in upper limit values of speeds and accelerations at which the shafts can operate. Therefore, the numerical control device sets the upper limit values of the speeds and the accelerations of the shafts in advance taking into account characteristics of a machine and performs acceleration-deceleration during machining such that the speeds and the accelerations do not exceed values of the set parameters.
As an acceleration-deceleration method used in the numerical control device, in general, there are post-interpolation acceleration-deceleration and pre-interpolation acceleration-deceleration. The post-interpolation acceleration-deceleration is a method of smoothing a position or speed for each of the shafts using a low-pass filter or the like having a problem in that a trajectory error occurs during a small circuit operation or at a corner. On the other hand, the pre-interpolation acceleration-deceleration is a method of performing interpolation after feed speed is accelerated or decelerated having an advantage that a trajectory error does not occur. However, the pre-interpolation acceleration-deceleration has a problem in that, because the speeds of the shafts are decelerated at a corner section to be continuous, a processing time increases or, if the deceleration is not applied much at the corner section, the speeds of the shafts become discontinuous and a mechanical vibration tends to be caused. In this way, both the methods have advantages and disadvantages. Therefore, it is necessary to properly use the methods according to an application, parallel use the methods, or adjust parameters (acceleration, etc.) for adjusting degrees of acceleration-deceleration of the methods according to machining. Therefore, there is a problem because this takes a lot of time and labor and requires an advanced skilled technique.